Polymer optical fibres are recognised as having potential application as low cost, broad bandwidth, easy-to-install waveguides. These features make them eminently suitable for use as relatively short length high speed data transmission lines, typically in local area network and residential signal transmission applications. Also, polymer optical fibres may be employed in the transmission of light at wavelength in the red and near infrared, this permitting the use of relatively cheap light sources.
Despite all of these potentially beneficial features, polymer optical fibres have not been produced at a significant commercial level. This is predominantly because of the need for large transverse optical intensity profiles (“spot sizes”) and the consequential constraints imposed by existing fabrication techniques. Large spot size fibres are required in order to permit relatively simple couplings and connections, particularly in the context of the intended applications of polymer optical fibres.
A polymer optical fibre having a traditional step index may be drawn with a large spot size, this providing for inexpensive installation of the fibre. However, such a fibre exhibits very large intermodal dispersion.
Single mode polymer optical fibre is difficult to produce and, in any case, the very small mode-size limits application of the fibre.
The technology required to produce graded-index polymer optical fibres is very complex and the inherent cost of producing the fibres at a commercial level is prohibitive.
Viable large spot size, single mode polymer optical fibres have been found to be almost impossible to produce using known fabrication techniques.